Reversible galvanic battery.



No. 871,214l PATENTED NOV. 19, 1907. T. A. EDISON.

REVERSIBLE GALVANIC BATTERY.

APPLICATION FILED 0OT.31, 1900.

Inventor nnrrnn sra'rns rafrnnr orrion.

THOMAS A. EDISON, OF LLEWELLYN'PARK, NEW JERSEY, ASSIGilORiTO EDISON STORAGE BATTERY COMPANY, OF ORANGE, NEW JERSEY, A CORPORATION OF NEW JERSEY.'

REVERSIBLE GALVANIC BATTERY.

Specification of Letters Patent.

Application tiled October 31. 1900. Serial No. 34.994.

Tocll 'whom 'it may concern: y

Be it known that I, THOMAS A. .Reisorg a citizen of the United States, residing at Llewell n Park, in the county of Essex and y State o New Jersey, have invented a certain new and useful Improvement in Reversible Galvanic Batteries, (Case No. 1,048,) olwhich the following is a description. a

My invent-ion relates to improvements iiy reversible galvanic cells or so-called storage batteries, and the object of the invention is to'provide and produce a battery oi this type which is light, portable and durable.

With the commercial storage or reversible galvanic cells now constructed, the solution is changed as the battery is charged or discharged, thereby requiring a crmsidcrable amount of liquid aiid,iiiakiiig the cell heavy and bulky. Thus in the case ot the lead sterage battery, suli`uric acid is taken from the liquid in the act of discharging. ln the case of the zinc and copper oxid battery with alkaline solution, the whole oi the zine is carried in' the solution, from which, in the act ol' charging, it is eleet-roplated upon a suitable electrode. W ith my improved reversible eralvanic cell, nothing is added to or takenA om the solution during the charging and discharging since the active materials are insoluble in all conditions of use and in conscquence a minimum quantity ol solution can 'employment of metallic receptacles for retalnin Y the lincly divided metals, which rebe employed, while a high condition ot perinanence will be secured as l will explain.

'My present improvements relate, iii the first place, to the use offlinely divided nictallic cadmium as the active clement, and to finely divided copper oxid as the negative element, both being employed in an alkaline solution.

The improvements further relate to the ceptac es are made of nickel or of some other metal, such as iron, suitably nickclplated.

The iinprovpn'ients further relate to the production of the lincly divided cadmium and copper in a proper condition l'or use in the battery; and, linally, to the construction of the battery a whole, and to the assembling and treatment'ol the elements entering into its makeup.

In order that the invention may be better understood, attention is directed ito the accompanying drawings forming part of this specification, and in which Figure 1 is a perspective view of one of the plates provided with receptacles for carrying the elements of the battery, Fig. 2 a plan thereof, and F ig. 3 a vertical sectional view showing a cell of four .elements properly elec 60 trically connected.

In all of the above views corresponding parts are represented by the saine numerals of reference.

The plates l., which are generally rcctanguiar in form and relatively thin, are made preferably of sheet nickel, but sheets ot iron or other metal ro )erly nickclplated can be utilized insteaii.) Illacli plate is provided with a trame surrounding the saine, which lraine is made also of nickel or of nickelplated metal, and said frame is connected to the plate l by nickel rivets 3 which are preterably fused in position by an electric arc op- `@rated in the well known .manner in order that perfect Contact between the traine and plate may be secured. The plates are provided with lugs 4, 4 at. their-bottoms, by means ot'v which all the plates ol the ccll may be mechanically connected together by the usual electrically insulated connecting bolts `l, and at their upper ends they are provided with lugs 5, by which the like elements ol' the cell may be connected electrically in the usual way; for instance., all of the negative plates may be l'ormed with lugs 5 at thc right, and the positive plates with these lugs at the lel't, so that the lugs may be connected together by bolts 5 passing directly through them. Secured to the plates l on one side thereof arc thc nickel or nickelplated pockets or receptacles 6, which are perforated as shown, and which contain the battery elcments. 'lhe plate as described is thc saine for the negative element clement, thereby materially reducing the cost ot their manufacture. i

ln manufacturing my battery, l lnd that the nickel going into the maken) ol the plates and pockets becomes coatedI with an 100 oxid due presumably to the annealing7 and which l lindycannot beplremoved by acids without all'ccting the plate. l therefore prefer to remove this oxid, in order that the as for the positive I Acles of the other plate of the pair is packed,Y

in the preferred insta-nce, iinely divided coper oxid as the negative elenient.

The iinely divided metallic cadmium is preferably obtained by an electrodeposition process, a very thin platinum wire being used as the cathode, a plate ot metallic cadmium as the anode, and a weak solution of sulfate of cadmium as the electrolyte. By employing a strong current in the electrolyte with a small platinum wire as the cathode as explained, the cadmium will be deposited thereon in its metallic state, exceedingly finely divided and iilamentary in formand of great purity. The deposited iinely divided cadmium is detached from time to time from 'the cathode, and is washed in water to rcniove any adhering sulfate oi' cadmium, after which it is packed in the perforated pockets 6 of the desired plates, which are then ready for use in the cells.

By reason of the iilamentary character of metallic cadmium, the packed mass within the perforated pockets Ican be made very coherent, while at the same time sullicienty porosity will be secured to permit the electrolyte to ell'ectively circulate through the saine.

ln the case of the preparation of the iinely divided copper oxid, greater' preparations are necessary in order that proper results may be secured. l ln all the attempts of previous experimenters to use copper oxid as a depolarizer in revcrsiblf` batteries, the phenomenon was observed ot the production ol' a small amount ol a copper salt, bluish in color, and which was soluble in the alkaline liquid With the previous experiments it was observed that this soluble salt in circulating in the solution was reduced to the metallic state by contact with the active metal (zinc l'or instance), producing local action and resulting in the rapid' deterioration of the elements. "lhe previous experimenters attempted to prevent the circulation of the soluble copper salt in the liquid by surrounding the copper element With a porous material, which while not preventing the currentllow, would to a certain extent retard the circulation of the soluble copper salt. The experiments referred to were, however, unsuccessful, for the reason that the porous material would not permanently prevent the circulation of thesoluble salt, and the peculiar porous materials which had to be used were themselves destroyed in time by the strong alkaline liquid' necessarily employed l for holding in solution a suiiicient quantity i of the active material. Such experiments Were also unsuccessful because a relatively large bulk of liquid was necessary, while the resistance of the cell was enormously increased. In consequence, reversible batteries using copper oxid as a depolarizer have now' obsolete. I have ascertained the cause L of the production of the soluble copper salt 1 referred to, and have prevented its formal tion entirely so as to overcome the objecltions which were met in practice by the ,T early experimenters with cells of this type. l Brieily stated, my discovery resides in the fact that when the copper is in very finely divided form, the production of the soluble salt is entirely overcome, since the eiectof the current is to make anhydrous and insoluble in the alkaline liquid any copper oxid which may be formed. li, on 'the other hand, there is a single piece, however minute, of dense copper, or even if the iinely divided copper is compressed sullicientlyto materially increase its density, a soluble liydroxid of copper will be l'ormed therefrom with the objections indicated. liurthermore, l iind that copper scale `cannot be employed with sat` ty o n account of its density after reduction to the metallic state, and also because it generally contains some unoxidized copper, l'rom which on reoxidation by the current the l blue hydroxid referred to will inevitably be lproduced. ln practice therefore, l 'preferl ably obtain the iinely divided copper by re- 5 duc/ing pure r:arbonate oi copperin the usual l way by hydrogen at the lowest possible temperature that will insure perfect reduction. i A material increase. in the temperature has been found to result in an objectionable inl crease in the density of the copper produced. When the copper has been thus secured in iinely divided form, it is molded into thin blocks of the proper shape to lit snugly in the pockets 6 of Vthe plates. The pressure used in molding these plates should not be greater easily handled without breakage, and care especially should be taken that the molding devices do not scratch or indent the plates to thereby locally increase the .density of the copper and thereby result in the objectionable Jformation of the blue hydroxid referred to. After the copper plates have been ber to a temperature vof not over five hundred degrees Fahrenheit for six or eseven hours until the copper is converted intoiits black oxid (C110). lf higher tein eratures are employed, the density of the b ack oxid will be undesirably increased. After being thus oxidized, the copper oxid blocks are renever remained in commercial use and are' than is necessary to permit the plates to be molded, they are subjected in a closed chaml duced electrolytically to metallic copper,

and are then reoxidized on charging by the current until they are converted into the red oXid (CuzO). In this form, the blocks are inserted in the perforated pockets 6 of the desired plates, which are then ready for use.

The iinely divided copper originally obtained by reduction by hydrogen as explained, may be lightly packed in the perforated receptacles without being first oxi- 10 dized by heat as described. I nd, however, thatwhen this is done, the .efficiency is not so high as'when the copper is first oxidized to the black oxid, because, unlike the cadmium,

it is not lamentary in form, and its parti- ),5 cles asoriginally produced do not apparently effect an intimate electrical contact withl 'each other. Finely divided copper ob-,iy

tained as'described or in'any other way, and

oizsuch a character as to prevent, when oxij dlzed, the formation of a soluble copper salt in an `alkaline solution, is not necessarily limited in its usein connection with a reversible galvamc cell employing cadmium as the activeelement, but on the contrary it may be j g5 `employed to advantage as a depolarizer in other alkaline solution cells wherein zinc, i'or example, 1s used as the active element.

The copper oxid and cadmium plates ob- -tained as I have explained, are then properly connectedthrough the lugs 4, 4, which are suitablyinsulated from each other, and by the lugs V 5.so that the like plates ol the cell will be elec- `trically connected. 'Ihc plates, after they have been thus aggregated,.are inserted in a k suitable jar 7, containing preferably about a ten percent solution 8 ol pure sodic hydroxid.

In operation, when the t tttery is discharged, the copperoxid is reduced to the metallic state,.while the metallic cadmium is 40 oxidized to cadmous oxid (CdZO). Upon recharging, the metallic state, while the copper is oxidized to copper oxid ((11120). ln the charging and discharging olI the cell, water l'rom k the liquid is respectively decomposed and regenerated, leavingr the liquid in exactly the Asame condition and quantity after each discharge. For this reason the amount ol liqi Vuid used may be very small, and in 'l'act l iind 150I in practice that by interposing between the v plates thin sheets of asbestos, or ol any suitable llght, owdered material not attacked y, bythe alka 1 such as oxid ol magnesium and `which `have been merely moistened with the alkaline liquid, nearly as good results cau be securedv as when the plates are actually im- 'mrsed in the solution. In this way I am the oxid ol cadmium is reduced to enabled to produce a reversible galvanic cell l which is in fact a so-called dry battery.

'Ihe voltage of my improved battery is .44 volts. Its internal resistance is extraordinarily small, and the output per pound ol' lcell exceeds that of any combination of (i which I have any knowledge. Furtherl more, exhaustive tests which have been made, have demonstrated that there is practically no deterioration, since neither nickel, nor cadmium nor any oi their oxids,nor copper, nor its anhydrous lower oxids, are soluble in the alkaline liquid, while there is no local action between the metallic cadmium and nickel, on account of the position of the two metals in the electric series. 'lhe jar or cell 7 for containing the elements maybe I made of nickel or iron or other metal nickelplated on its interior and hermetically sealed as to the liquid, a gas vent 9 being alone necessary to permit the escape of' gases which may be generated in case the battery is overcharged.

llaving now described my invention, what I claim as new and desire to secure by Letters Iatent is as follows:

1. In a reversible galvanic cell, an alkaline I solution; an electrode consisting ol' an insolul ble metallic perforated inclosing pocket, and a finely divided insoluble active. material tightly packed in such inclosing pocket; and a secoml-electrode, substantially as set forth.

2. ln a reversible'galvanic cell, an alkaline solution; and an electrode therein comprising an insoluble electrode plate, a series of insoluble metallic perforated int-losing pockets carried by said plate, and an insoluble active material tightly packed in said pockets; and a second electrode, substantially as set forth.l

3. A reversible galvanic cell, comprising an alkaline solution, a positive clement coln posed ol' inely divided cadmium in filamentary lorm and a suitable negative lelectrode,l

, 'rnoMAs A. ijoisovV Witnesses:

J. F. RANnoLrH, i J. A. Boni-IME. 

